PNIVEB8ITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


IMPROVEMENTS   IN    METHODS  OF 
PICKLING  OLIVES 


BY 

FREDERIC   T.  BIOLETTI  and  W.  V.  CRUESS 


BULLETIN  No.  289 

December,   1917 


UNIVERSITY  OF  CALIFORNIA  PRESS 
BERKELEY 
1917 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPEKIMENT  STATION  STAFF 

HEADS  OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 
*  Robert  H.  Loughridge,  Soil  Chemistry  and  Physics   (Emeritus). 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

J.  B.  Davidson,  Agricultural  Engineering. 

Elwood  Mead,  Rural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

W.  L.  Howard,  Pomology. 
|Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 

O.  J.  Kern,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Rogers,  Olericulture. 

David  N.  Morgan,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

DIVISION  OF  VITICULTURE  AND  ENOLOGY 

Frederic  T.  Bioletti  W.  V.  Cruess 

F.  C.  H.  Flossfeder  J.  R.  Zion 

G.  Barovetto  A.  E.  Way 


*  Died  July  1,  1917. 

f  In  co-operation  with  office  of  Public  Roads   and  Rural   Engineering,   U.    S. 
Department  of  Agriculture. 


IMPROVEMENTS  IN  METHODS  OF 
PICKLING  OLIVES 

BY 

FREDERIC  T.  BIOLETTI  and  W.  V.  CRUESS 


I.  EXTRACTION  AND  DARKENING  OF  RIPE  OLIVES 

Defects  of  Present  Methods. — In  most  Calif ornian  factories,  ripe 
olives  are  first  treated  with  a  lye  which  is  allowed  to  penetrate  the 
skin  and  a  short  way  into  the  flesh.  This  lye  is  then  drained  off  and 
the  olives  are  exposed  to  the  air  to  darken.  When  the  desired  color 
is  reached,  a  second  lye  is  applied  and  allowed  to  reach  the  pit  to 
destroy  the  bitterness.  This  lye  is  then  washed  out  with  water,  which 
is  changed  frequently.  There  are  many  variations  of  this  general 
process.  Some  factories  use  several  lyes  and  several  exposures  to  the 
air.  The  strengths  of  lye  used  vary  greatly.  But  in  general,  the 
process  most  in  use  is  one  of  exposure  to  air  to  darken  the  color  after 
a  first  lye  treatment,  followed  by  one  or  more  lye  treatments  to  destroy 
the  bitterness  and  repeated  soakings  in  water  to  remove  the  lye. 

Exposure  to  air  produces  other  effects  besides  darkening  the  color. 
It  toughens  the  flesh  and  injures  the  flavor.  The  darkening,  which  is 
desirable  if  confined  to  the  outer  parts  of  the  olive,  may  extend  to 
all  the  flesh,  where  it  is  unattractive.  Desirable  qualities  in  a  ripe 
picked  olive  are:  Dark  color  (localized  near  the  skin),  light  colored 
flesh  (tender,  but  not  soft),  "freestone"  pits  (i.e.,  separating  easily 
from  the  flesh),  and  a  rich  flavor,  not  "scorched"  nor  " oxidized. ': 
It  is  very  difficult  to  obtain  all  of  these  qualities  by  the  "exposure" 
method,  even  if  ripe  fruit  is  used  and  it  is  impossible  with  under- 
ripe fruit.    The  method  is  lengthy,  usually  requiring  several  weeks. 

Theory  of  Air  Exposure. — In  the  usual  methods,  the  olives  are  first 
bleached  by  the  lye  and  then  darkened  by  direct  exposure  to  the  air. 
The  darkening  is  evidently  due  to  the  oxygen  of  the  air.  If  oxygen 
were  supplied  in  some  other  way,  while  the  olives  remained  in  the 
liquid,  darkening  should  occur  equally. 

This  principle  has  long  been  applied  in  the  old  method  of  removing 
the  lye  and  bitterness  by  running  water.  The  olives  are  darkened 
by  the  air  dissolved  naturally  in  the  water,  but  the  process  is  slow. 
The  stirring  of  olives  in  the  pickling  vats  with  compressed  air,  as  is 


196  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

done  in  many  factories,  also  darkens  the  olives  somewhat,  but  as  at 
present  practised  the  darkening  is  slow  and  imperfect. 

New  Method  A. — Laboratory  experiments  at  the  University,  ex- 
tending over  several  years,  and  recent  factory  tests,*  have  demon- 
strated that  the  continual  movement  of  the  liquids  and  their  continual 
aeration  can  be  combined  with  good  effects.  The  dissolved  and  occluded 
oxygen  darkens  the  color  and  the  flowing  liquid  equalizes  and  hastens 
the  action  of  the  lye,  water,  or  brine.  Water  treated  and  used  in 
this  way  greatly  increases  the  rate  of  darkening  and  of  the  removal 
of  the  lye  and  bitterness. 

The  quality  of  olives  treated  by  this  method  was  superior  to  that 
of  the  same  olives  treated  in  the  usual  way,  and  the  time  was  shortened, 
both  in  laboratory  and  factory  tests,  to  72  hours,  for  the  whole  process 
from  fresh  olive  to  finished  product. 

The  best  and  most  economical  installation  for  applying  this  method 
can  be  developed  only  in  actual  practice,  but  a  workable  device  is 
shown  in  Figure  A. 

The  olives  are  first  placed  in  the  vats  g,  g,  which  can  be  probably 
be  of  any  convenient  size.  They  are  then  covered  with  lye  (2  ounces 
per  gallon)  which  has  been  heated  to  75°  or  80°  F.  Some  of  the 
same  lye  is  placed  in  the  sump  a.  The  rotary  pump  d  is  then  started 
and  the  warm  lye  forced  from  the  sump  through  the  pipes  leading  to 
the  bottoms  of  the  vats  of  olives.  The  small  pet  cock  c  is  opened  at  the 
same  time.  This  allows  air  to  be  drawn  into  the  liquid  by  the  suction 
of  the  pump. 

The  lye  passes  up  through  the  olives  and  overflows  through  the 
outlets  h  to  the  return  pipe  j,  and  back  to  the  sump  a,  where  the 
cycle  recommences.  This  circulation  is  kept  up  until  the  lye  has 
penetrated  to  the  pit.  The  lye  is  then  drawn  off  and  replaced  with 
water  which  is  caused  to  circulate  through  the  system  in  the  same  way. 
The  pet  cock  c  is  kept  open.  Air  is  drawn  in  and  mixes  intimately 
with  the  water  in  the  pump  and  pipes.  The  aerated  water  which  is 
kept  at  75°  to  90°  F.  by  the  steam  jacket  e  rapidly  darkens  the  olives 
and  washes  out  the  lye.  The  water  should  changed  at  least  twice  a 
day.  When  the  lye  has  been  washed  out  and  the  color  sufficiently 
darkened,  the  olives  are  placed  in  cans.  Brine  is  then  added  and  the 
cans  exhausted,  sealed,  and  processed  in  the  usual  way. 

This  method  may  be  modified  by  using  two  lye  solutions,  the  first 
just  entering  the  skin  and  the  second  reaching  to  the  pit.     Each  lye 

^Factory  tests  of  Method  A  were  made  at  the  works  of  Hunt  Bros  Co.,  who 
supplied  the  necessary  facilities.  The  successful  carrying  out  of  both  the  labora- 
tory and  factory  work  was  due  in  great  part  to  the  efficient  assistance  of  Mr.  J.  B. 
Zion. 


IMPROVEMENTS    IN    METHODS    OF   PICKLING   OLIVES 


197 


« 


FIG.  ft 


U 


3 


A 


.^_ 


SF 


CJf     sum  p 

b     PUMP  /NTfWC 
C     /HP  /NLCT 
Ci-     POM  P 

f  WAT£P  OUTICTS. 
TO    WTO. 

f/=rctxLiNG  vats. 
L .  lowep  w/9T  own.  cry 

J.    SU/1P   PCTUPN   PtPC. 
/(      TtiCn  rto/VS  T£1P 


m 


//G.ft.Sl/GGCSTC'D     AF>/=>fl/?flTUS   fOff   C//=?CJLf?T/MG 
flZ/ffiTCD    IV/?T£ft    /f/YD    C//=TCULftT//VG    HOT 
tV/iTCff  AfET/iOOS. 


a 


U 


f 


f/a& 


-^ 


t 


O.   cortrfTcssz-o  /»//?  supply 

C-     YT)T   OUTCCTS. 
d     tV/9  57-^    PVPC 

C    w  siren  /icprcn 

A      S/OT    WffTZ/T      OUT/-CTS 


,b 


/7S.3    StT£TCH    Or  /?/=>/=/} ff/fTVS  SUGGESTED    FOR   C0A/3//V£D    USL    OF  HOT 


WaTE/l  SUPPLY 


II — II — irnr 
rteftPT/o/v  ey 

^r/GJD.  i 


£ 


I 11 1 

sp/T/ry/s*e 

/7G  jD-2 


//G.C.     /=l/i/v     or  Di5T/fiDUT/ON  or 

COMPRESSED  /?//?    EVrT   METHOD    £} 


//GJD    Two    orr/cr?  '/vs/yyoos  or 
£>£/-  /VET?  /A/G    /9/V£>  /?£/?/*/  r//V  O 
E/QU/OS    /NAfET/iCD     /f 


198  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

solution  is  followed  by  circulating  aerated  water,  the  first  until  the 
olives  are  sufficiently  darkened,  the  second  until  all  lye  and  bitterness 
have  been  removed.  This  method  requires  more  time  than  the  single 
lye  treatment  and  seems  to  have  no  advantage  over  it. 

Other  methods  of  aeration  may  be  substituted  for  the  air  inlet  c. 
In  that  of  Figure  D-l,  the  liquid  is  aerated  by  allowing  it  to  splash 
into  the  vat ;  in  that  of  Figure  D-2,  by  spraying  through  fine  openings 
in  the  outlet  pipe.  The  method  of  Figure  A,  however,  seems  to  be 
the  most  simple,  thorough,  and  easily  regulated. 

New  Method  B. — The  underlying  principles  of  this  method  are 
high  temperature  and  circulating  liquid.  The  same  apparatus  may 
be  used  as  for  Method  A.  The  water  and  lye  are  caused  to  circulate 
as  in  Method  A,  but  the  pet  cock  c  is  kept  closed  and  no  attempt  is 
made  to  aerate  the  liquids.  A  lye  of  2  ounces  per  gallon  is  used  at 
approximately  100°  to  110°  F.  When  the  lye  reaches  the  pit  it  is 
removed  and  replaced  by  water.  The  water  is  heated  to  between  100° 
and  175°  F.,  by  the  heater  e  and  kept  at  this  temperature.  It  is 
pumped  continuously  until  the  proper  color  is  reached  and  the  lye 
removed. 

This  method  gave  better  results  on  a  laboratory  scale  than  Method 
A,  but  was  not  tested  on  a  factory  scale.  It  is  recommended  for  trial 
by  factories  this  season  in  preference  to  Method  A. 

The  heating  device  shown  is  an  improvised  steam  jacket  around 
the  water  supply  pipe.  For  experimental  purposes,  hot  water  from 
a  tank  may  be  used  and  allowed  to  go  to  waste  as  it  overflows  from 
the  pickling  vat,  but  for  factory  installations,  the  water  should  be 
used  repeatedly  to  avoid  the  excessive  cost  of  operation  due  to  the 
large  quantity  of  water  used. 

New  Method  C. — In  this  process,  an  apparatus  such  as  that  shown 
in  Figure  B  is  used.  The  principles  involved  are  aeration  by  com- 
pressed air  and  use  of  hot  standing  liquid.  The  olives  are  placed  in 
the  vats  o,  b.  A  lye  of  two  ounces  per  gallon  at  100°  to  110°  F.  is 
then  added.  Compressed  air  from  the  perforated  pipes  a,  a,  is  passed 
continuously  through  the  olives  and  the  lye  is  allowed  to  reach  the 
pits.  The  lye  is  then  replaced  by  water  at  100°  to  185°  F.,  from 
the  pipes  /,  /.  Compressed  air  is  then  passed  as  before,  through  the 
liquid  and  olives  from  the  pipes  a,  a  (see  also  Figure  C).  The  water 
is  replaced  by  fresh  hot  water  from  /,  /  as  it  cools.  It  should  be 
maintained  at  120°  to  150°  F.,  or  above.  The  water  is  not  caused 
to  circulate,  but  is  agitated  violently  by  the  air  jets. 

This  process  also  has  been  tested  on  a  laboratory  scale  only,  but  is 
strongly  recommended  for  trial  experimentally  by  factories  already 


IMPROVEMENTS   IN    METHODS   OF   PICKLING   OLIVES  199 

equipped  with  compressed  air.  It  did  not  work  quite  so  rapidly  as 
methods  A  and  B,  but  gave  excellent  results. 

New  Method  D. — This  method  combines  the  three  principles  of 
aeration  and  circulation  of  liquid,  and  high  temperature.  The  appa- 
ratus of  Figure  A  is  used.  The  method  is  the  same  as  Method  A, 
except  that  the  temperature  is  maintained  at  100°  to  175°  F.  The  air 
cock  c  is  left  open  or  the  liquid  is  aerated  by  devices  shown  in  Figures 
D-l  and  D-2. 

This  method  is  very  rapid  and  probably  the  best  of  the  four 
suggested. 

FERMENTATION  OF  PICKLED  OLIVES 

The  green  pickled  olives  of  commerce  usually  known  as  "Queen" 
olives  are  prepared  by  a  fermentation  process.  This  fermentation 
produces  lactic  acid  which  gives  them  their  peculiar  piquancy  and 
helps  to  preserve  them. 

Experiments  at  the  University  have  shown  that  pickles  practically 
identical  in  character  and  quality  with  the  imported  Queen  olives 
can  be  produced  in  California  from  the  Sevillano  and  Mission  varie- 
ties.    The  Manzanillo  can  be  prepared  successfully  in  the  same  way. 

Other  experiments  have  shown  that  this  pickling  process  can  be 
applied  successfully  to  ripe  olives,  at  least  to  the  Ascolano  variety. 

It  has  been  shown  also  that  ripe  olives,  pickled  in  the  usual  way, 
or  by  the  methods  described  here  can  be  given  the  piquant  quality  by 
a   supplementary   fermentation. 

Green  Olives. — The  olives  are  picked  after  they  have  reached  a 
good  size,  but  before  they  show  any  sign  of  coloring,  either  red  or 
yellow. 

They  are  placed  in  a  2%  lye  (2%  ounces  of  lye  per  gallon  of  water) 
and  left  until  the  lye  reaches  the  pit.  The  lye  is  then  replaced  by 
water  changed  twice  daily  until  all  taste  of  lye  has  disappeared. 

They  are  then  placed  in  7%  brine  (9  ounces  of  salt  per  gallon  of 
water). 

All  these  operations  should  be  carried  out  with  as  little  exposure 
of  the  fruit  to  the  air  as  possible. 

The  olives  are  kept  in  the  brine  in  closed  receptacles  at  ordinary 
room  temperatures  until  fermentation  has  developed  the  characteristic 
flavor  and  acidity.  This  will  require  from  three  weeks  to  several 
months,  according  to  the  temperature  and  to  the  amount  of  flavor 
desired. 

When  the  fermentation  has  reached  the  desired  point,  the  brine  is 
taken  off,   strained,   or  filtered,   and  boiled.     The   olives   are  rinsed 


200  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

quickly  with  water  and  then  covered  with  the  hot  brine.    They  may  be 
kept  in  barrels,  or  preserving  jars  without  further  treatment. 

If  intended  for  shipment  or  to  be  kept  for  a  long  time,  they  may 
be  placed  in  glass  preserving  jars  or  lacquered  cans.  These  are  then 
filled  with  the  boiling  brine,  sealed,  and  heated  at  212°  F.  for  about 
20  minutes. 

Ripe  Olives  of  Green  Color. — The  Ascolano  olive  gathered  just  as  it 
was  turning  cherry  red,  the  stage  of  ripeness  considered  best  for  ripe 
olives,  was  pickled  by  the  fermentation  method  just  described.  The 
result  was  a  light  greenish  yellow  pickle  with  white  flesh,  crisp,  and  of 
excellent  flavor.  It  had  none  of  the  fibrous  character  of  many  green 
olives  and  was  considered  much  superior  by  everyone  who  tasted  them. 
It  is  probable,  that  olives  of  any  variety  could  be  prepared  in  the  same 
way,  provided  they  had  not  become  black.  The  method  offers  a 
simple  method  of  producing  a  new  kind  of  pickled  olive  that  might  be 
preferred  to  either  the  green  or  the  black. 

Fermented  Ripe  Olives  of  Black  Color. — Ripe  olives  which  have 
been  pickled  in  any  of  the  ordinary  ways  may  be  subjected  to  a 
fermentation  that  gives  them  some  of  the  sprightliness  of  the  green 
olives  and  improves  them  to  many  tastes. 

When  the  ripe  olives  have  been  pickled  and  are  ready  to  can,  they 
are  placed  in  a  7%  brine  and  allowed  to  ferment  in  exactly  the  same 
way  as  described  for  green  olives.  The  fermentation  bleaches  the 
olives  a  little,  but  they  can  be  darkened  by  exposing  to  the  air  for 
a  day  or  two.  They  may  be  packed  in  the  filtered  and  boiled  brine 
like  the  green  olives,  but  the  best  results  are  obtained  by  putting  them 
in  lacquered  cans  or  glass  jars  without  liquid.  They  are  first  heated 
with  boiling  brine,  the  brine  poured  off,  and  then,  after  sealing,  the 
cans  are  sterilized  30  minutes  and  the  jars  40  minutes  at  212°  F. 

At  present,  we  have  two  main  types  of  pickled  olives :  That  rep- 
resented by  the  green  Spanish  "Queen"  olives  and  that  represented 
by  the  Californian  black  ripe  olives.  The  latter  is  more  nutritious 
and  wholesome,  while  the  former  has  a  sprightliness  of  flavor  relished 
by  many.  The  green  olive  is  hard,  tough,  and  indigestible;  the  ripe 
often  flat  and  insipid  to  many  tastes. 

.  The  two  methods  of  pickling  ripe  olives  by  fermentation  described 
here  combine  the  good  qualities  of  both  types  and  avoid  their  defects. 
The  second  method  yields  a  black  olive,  and  the  first,  one,  which  while 
equally  ripe  and  wholesome,  is  green  or  whitish  in  color.  The  first  is 
simply  a  probable  improvement  of  our  present  type  of  ripe  olives, 
but  the  second  produces  an  entirely  new  type. 


